Microwaves

Regarding microwaves and objects, in general microwaving is not
something to be done casually.  Household type microwave ovens, in
particular, are a problem.  Martine Gillet and Chantal Garnier at CRCDG
in Paris raised the point during a presentation of their study that
household microwave ovens are not even enough and generate dangerous
"hot" spots.  Consider how many microwave ovens handle frozen butter --
I have seen a number that leave most of the block frozen, but melt
discreet holes right through. In addition, they warn about cooking sea
food, chicken and pork in the microwave oven because, while 99% of meat
may be cooked, there are raw spots that have caused a fair number of
people to get parasites.  The second problem with household microwave
ovens is wave disorder.  Plane objects require single-mode wave guides
for good energy transfer.  (See Brandt (A.C.), Berteaud (A.J.). -
Sechage par microondes pour la restauration de documents de papier en
feuille ou en cahier.  Studies in Conservation, 32, 1987, pp 14-24. The
article is in French.)

Even with special equipment, the point has been raised about the effect
of microwaves on various organic materials such as glues and covers on
books. Some materials may very well melt.

Finally, Brandt and Berteaud raised the point about possible
dehydration.

If you will trust my French, I'll paraphrase/translate one table.

Type of paper           % water in         % water after
                        dry paper           10 minutes
                                          under microwaves
                                            (800 watts)

Journal                    8.22                4.4
Chiffon   125g/sq M        6.10                2.85
          224g/sq M        5.52                2.06

For these reasons microwave treatment is probably not a good idea for
now especially when books are so complex and may react in so many ways.

-Doug

                                  ***
                  Conservation DistList Instance 5:18
               Distributed: Wednesday, September 4, 1991
                        Message Id: cdl-5-18-004
                                  ***